Project Summary While much is known about the prevalence, incidence and risk factors associated with problem gambling at the population level, less is known about the nature of the relationships between risk factors and gambling, as well as the actual behavioral mechanisms that govern the development and maintenance of gambling. The present research aims to develop and test an innovative animal model of slot machine gambling with pigeons using a token economy. The rigorous control permitted by laboratory methods enables an experimental investigation of the development and maintenance of gambling behavior, as well as for testing some of the key hypotheses advanced to account for gambling. The research grows out of recent grant-funded work in our laboratory that demonstrates the utility of studying economic decisions in a self- contained miniature economy from a behavioral economic perspective. The present research would extend these methods and theoretical concepts to gambling decisions, bringing sophisticated experimental and quantitative techniques to bear on this critically important but poorly understood phenomenon. More specifically, the project consists of an interrelated series of experiments that seeks to quantify the relationships between gambling behavior and (a) reward variables (size and probability of wins and losses), (b) economic variables (wage rate/salary, income, budget, gambling costs), (c) contextual variables (effects of near-wins and near-losses, the presence/absence of cues and signals), and (d) social enrichment variables (housing conditions outside the experiment). In all branches of the project, animals decide whether to earn, accumulate, spend, or gamble tokens in a self-contained economic environment. The use of token rewards, a monetary-like currency, provides a more ecologically valid model of gambling behavior than prior laboratory-based models, and opens the experimental investigation of gambling in fruitful new directions. Data from these experiments will shed light on the behavioral mechanisms of gambling, an important first step in elucidating neurochemical mechanisms and potential clinical applications. Such work is thus of theoretical as well as applied significance.